UC Santa Cruz

We have studied experimentally and theoretically the cross-plane Seebeck coefficient of short period InGaAs/InAlAs superlattices with doping concentrations ranging from 2x10(18) up to 3x10(19) cm(-3). Measurements are performed with integrated thin film heaters in a wide temperature range of 10-300 K. It was interesting to find out that contrary to the behavior in bulk material the Seebeck coefficient did not decrease monotonically with the doping concentration. We did not observe a sign change in the Seebeck coefficient at dopings where the Fermi energy is just above a miniband. This is a sign that electrons' lateral momentum is conserved in the transport perpendicular to superlattice layers. A preliminary theory of thermoelectric transport in superlattices in the regime of miniband formation has been developed to fit the experimental results.